US3743938A - Closed data loop test apparatus for data transmission modem - Google Patents

Closed data loop test apparatus for data transmission modem Download PDF

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Publication number
US3743938A
US3743938A US00170428A US3743938DA US3743938A US 3743938 A US3743938 A US 3743938A US 00170428 A US00170428 A US 00170428A US 3743938D A US3743938D A US 3743938DA US 3743938 A US3743938 A US 3743938A
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Prior art keywords
modem
data
signal
frequency
receiver
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Expired - Lifetime
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US00170428A
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English (en)
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S Davis
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General Datacomm Inc
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General Datacomm Inc
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Assigned to FIRST PENNSYLVANIA BANK N.A. reassignment FIRST PENNSYLVANIA BANK N.A. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GENERAL DATACOMM INDUSTRIES, INC.
Assigned to AETNA LIFE INSURANCE COMPANY reassignment AETNA LIFE INSURANCE COMPANY SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GENERAL DATACOMM INDUSTRIES, INC., 1579 STRAITS TURNPIKE, MIDDLEBURY, CT. 06762, A CORP. OF DE.
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Assigned to GENERAL DATACOMM INDUSTRIES, INC. reassignment GENERAL DATACOMM INDUSTRIES, INC. NOTICE OF RELINQUISHMENT OF SECURITY AGREEMENT Assignors: FIRST PENNSYLVANIA BANK, N.A.
Assigned to GENERAL DATACOMM INDUSTRIES, INC. reassignment GENERAL DATACOMM INDUSTRIES, INC. RELEASE OF SECURITY INTEREST Assignors: AETNA LIFE INSURANCE COMPANY
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/24—Testing correct operation
    • H04L1/242—Testing correct operation by comparing a transmitted test signal with a locally generated replica
    • H04L1/243—Testing correct operation by comparing a transmitted test signal with a locally generated replica at the transmitter, using a loop-back

Definitions

  • ABSTRACT [22] Filed: Aug. 1971 A method and apparatus are provided for operating a I remotely located data transmission modem in a loop- [21] Appl. No.: 170,428 back test on the digital or data output side of the A modern in order to permit remote testing of the modem [52] US Cl U 325/67 179/2 DP, 179/15 BF unit and interconnecting transmission system.
  • Control 325/2 325/3 apparatus is utilized in a local modem to send a center- [51] Int Cl 04b 1/60 H04j 3/12, H04m 11/00 frequency command signal that is sensed at the remote 58 Field of Search 325/2, 3, 67, 363; mdem aummat'cany the respect mPut 179/2 DP 15 BF and output data leads.
  • a second command signal transmitted from the local modem is sensed at the remote [56] Reerences Cited modem to restore that modem to normal operation.
  • the present invention is related to data transmission systems and more specifically to duplex type modems which provide for simultaneous two-way transmission of data on a transmission circuit such as a two-wire telephone line.
  • modems provide for modulation of a carrier by a stream of data bits received from a business or data-processing machine, transmission of the data modulated carrier over a conventional telephone circuit and recovery of the data bits at the receiving end by a carrier demodulator.
  • a method and means are provided for remotely testing an unattended data transmission modem on a channel basis by control circuits that operatively connect and disconnect the respective input and output data leads in response to test command signals generated by a local modem.
  • the local modem is caused to generate a center-frequency command test signal for a predetermined period of time that is detected at the remote modem and utilized to control the connection of the data input and output terminals. Controlled dropout of the carrier generated by the local modem is used to terminate the closed data loop test.
  • the apparatus of the present invention may be advantageously used in combination with the time division multiplexer described in pending application Ser. No. 40,006 filed May 25, 1970 by Reymond et al. entitled Programable Asynchronous Data Buffer Having Means To Transmit Error Protected Channel Control Signals".
  • the error protected secondary control signals that can be transmitted in any selected channel may be utilized with the present invention to test an entire data transmission system including the digital interface at the remote end of the system.
  • FIG. 1 is a simplified functional block diagram illustrating a typical data transmission system in which the data loopback test maybe used
  • FIG. 2 is a simplified block diagram showing preferred means of the invention for providing data loopback test of a remote modem controlled by signals generated at a local modem;
  • FIGS, 3A-D are timing and waveform diagrams of the test initiate signals generated at the local modem.
  • FIGS. 4AD are timing and waveform control signals generated at the remote modem for control of the data I loop-back test.
  • FIG. 1 there is shown a modem 20 having data input and output terminals 21 and 22 and modulated carrier input and output terminals 23 and 24 as shown. Means areprovided for remotely testing the transmitter and receiver sections of modem 20 together with transmission lines 23 and 24 by circuits which operate to interconnect the transmitter and receiver terminals 21 and 22 as indicated by arrow 25.
  • each modem transmitter is provided with test initiate control apparatus that causes test response circuits in the cooperating remote modem receiver to interconnect the data input output terminals 21A, 22A by lead 25.
  • test initiate control apparatus that causes test response circuits in the cooperating remote modem receiver to interconnect the data input output terminals 21A, 22A by lead 25.
  • Loopback testing is initiated by actuation of switch 40 to its on position either by manual operation or by operation of solenoid 41 in response to a test control signal that may have been generated at another remote station and transmitted as a channel test signal in a cooperating time division multiplex system.
  • Closure of switch 40 provides a timed D-C control signal that momentarily opens switch to disconnect the digital input signals and at the same time key the FSK oscillator in transmitter 308 to its nominal center frequency for a period longer than the normal mark or space intervals, e.g. about 2 seconds.
  • an output signal is taken from the receivers FM detector, supplied to a double limiter or slicer and in turn to integrator 56.
  • the time constant of integrator 56 is selected so as to respond to the center-frequency discriminator output in about one and one-half seconds as shown in FIG. 4D and at the same time produce no output in response to the shorter duration mark and space data modulation.
  • the double-pole, doublethrow switch contacts 62A, 62B are connected so as to close the data test loop via 25 and at the same time disconnect the respective output and input lines 22 and 21 from 22A and 21A.
  • FIGS. 3A-3D show, respectively, the timing and waveform diagrams for switch 40, test initiate pulse 42, test reset pulse 70 and carrier frequency output signal 80.
  • Control pulses 42 and 70 may both be generated by conventional one-shot generators.
  • FIGS. 4A-4D are waveform and timing diagrams illustrating the response of the remote receiver control circuits to incoming signal 80 which produce control signals 70R and 60.
  • a duplex data transmission modem having a receiver with an input terminal for receiving a frequencyshift data modulated carrier signal and an output terminal to which is supplied data signals demodulated from the input carrier signal; and a transmitter having an input terminal for receiving digital data signals and an output terminal to which is supplied a carrier signal frequency-shift modulated by the input digital data signals, means for closed loop testing the operation of said modem from the carrier signal side of said modem comprising:
  • a. first circuit means including an FM detector for sending a first signal supplied to the receiver input terminal and producing in response thereto a test initiate signal, said first signal having a frequency between those frequencies used for the transmission of data;
  • switch means responsive to said test initiate signal for interconnecting the data output terminal of said receiver to the data input terminal of said transmitter, said switch means being further responsive to said reset signal to terminate the closed loop test by disconnecting the respective interconnected output and input data terminals.
  • the second circuit means includes a carrier amplitude detector for sensing interruption in the carrier signal supplied to said receiver input terminal and producing in response thereto a reset signal.
  • a duplex data transmission modern having a receiver with an input terminal for receiving a frequencyshift data modulated carrier signal and an output termi nal to which is supplied data signals demodulated from the input carrier signal; and a transmitter having an input terminal for receiving digital data signals and an output terminal to which is supplied a carrier signal frequency-shift modulated by the input digital data signals, means for closed loop testing the operation of said modem from the, carrier signal side of said modem comprising:
  • a. oscillator means for generating and supplying to the input terminal of the receiver a carrier signal
  • first switch means connected to said oscillator for shifting the operating frequency to a first frequency between those frequencies used for the transmission of data
  • first circuit means including an FM detector for sensing the first frequency signal supplied to the receiver input terminal and producing in response thereto a test initiate signal;
  • switch means responsive to said test initiate signal for interconnecting the data output terminal of said receiver to the data input terminal of 'said transmitter, said switch means being further responsive to said reset signal to terminate the closed loop test by disconnecting the respective interconnected output and input data terminals.
  • oscillator is a frequency shift keyed oscillator in a local modem connected by a data transmission system to the modem that is closed loop tested.
  • the second circuit means includes a carrier amplitude detector for sensing interruption in the carrier signal supplied to said receiver'input terminal and producing in response thereto a reset signal.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Maintenance And Management Of Digital Transmission (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Bidirectional Digital Transmission (AREA)
  • Dc Digital Transmission (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)
  • Communication Control (AREA)
US00170428A 1971-08-10 1971-08-10 Closed data loop test apparatus for data transmission modem Expired - Lifetime US3743938A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US17042871A 1971-08-10 1971-08-10

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US3743938A true US3743938A (en) 1973-07-03

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US00170428A Expired - Lifetime US3743938A (en) 1971-08-10 1971-08-10 Closed data loop test apparatus for data transmission modem

Country Status (8)

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US (1) US3743938A (de)
JP (1) JPS5528449B2 (de)
BE (1) BE787359A (de)
CA (1) CA951381A (de)
DE (1) DE2231869C3 (de)
FR (1) FR2150020A5 (de)
GB (1) GB1399659A (de)
IT (1) IT959320B (de)

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892923A (en) * 1972-08-16 1975-07-01 Philips Corp Supervision arrangement for a pulse code-modulation system
US3952163A (en) * 1972-04-24 1976-04-20 General Datacomm Industries, Inc. Method and apparatus for testing in FDM system
US4004097A (en) * 1975-01-03 1977-01-18 Badger Meter, Inc. Automatic meter reading device
US4013956A (en) * 1974-05-09 1977-03-22 U.S. Philips Corporation Telecommunication system with automatically switched modems
US4039751A (en) * 1972-04-24 1977-08-02 General Datacomm Industries, Inc. Method and apparatus for closed loop testing of first and second modulators and demodulators
US4055808A (en) * 1976-05-20 1977-10-25 Intertel, Inc. Data communications network testing system
US4064459A (en) * 1975-07-09 1977-12-20 Siemens Aktiengesellschaft Method of automatically testing the serviceability of a data transmission system
US4129756A (en) * 1976-09-24 1978-12-12 Le Material Telephonique Telephone exchange signalling unit
FR2423934A1 (fr) * 1978-04-17 1979-11-16 Cea Elektronik Automat Gmbh Dispositif a boucle pour installation de transmission de donnees
US4247934A (en) * 1978-07-01 1981-01-27 Te Ka De Felten & Guilleaume Fernmeldeanlagen Gmbh Testing system for data transmission paths
US4271514A (en) * 1978-09-06 1981-06-02 Te Ka De, Felten & Guilleaume, Fernmeldeanlagen Gmbh Loopback test for data transmission paths
US4402082A (en) * 1980-10-31 1983-08-30 Foster Wheeler Energy Corporation Automatic line termination in distributed industrial process control system
US4498186A (en) * 1980-10-10 1985-02-05 At&T Bell Laboratories Data set diagnostic system
US4530085A (en) * 1982-04-07 1985-07-16 Hitachi, Ltd. Reconfiguration control method for a loop-type data network
US4529979A (en) * 1981-09-07 1985-07-16 Hitachi, Ltd. Remote return loop control in a data transmission system
US4607139A (en) * 1983-06-30 1986-08-19 International Business Machines Corp. Interface module for telephone lines
US4766594A (en) * 1985-05-20 1988-08-23 Fujitsu Limited Digital network system having arrangement for testing digital subscriber line
US4977579A (en) * 1984-06-14 1990-12-11 The United States Of America As Represented By The Secretary Of The Navy Test set for a navigational satellite receiver
US5272705A (en) * 1991-04-15 1993-12-21 Mitsubishi Denki Kabushiki Kaisha Semiconductor integrated circuit device
US5463633A (en) * 1994-02-22 1995-10-31 Rockwell International Corporation Use of at commands to test modem with HP3065
US5881066A (en) * 1995-03-01 1999-03-09 Lepitre; Didier System for testing a transmission link
US20080089492A1 (en) * 2004-08-11 2008-04-17 BSH Bosch und Siemens Hausgeräte GmbH Circuit Arrangement for Suppressing Interference Signals in the Receive Branch of a Modem of a Household Appliance
US20080095220A1 (en) * 2004-08-13 2008-04-24 Bsh Bosch Und Simens Hausgerate Gmbh Circuit Arrangement for Suppressing Interfering Signals in the Receiving Branch of a Modem of a Household Appliance

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5320707A (en) * 1976-08-10 1978-02-25 Nippon Telegr & Teleph Corp <Ntt> Automatic return system for subscriber line base band transmission system
JPS54159105A (en) * 1978-06-07 1979-12-15 Hitachi Ltd Multiple signal-distribution unit
JPS59222943A (ja) * 1983-06-01 1984-12-14 Hitachi Ltd 半導体装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840797A (en) * 1952-08-14 1958-06-24 Westinghouse Electric Corp Supervisory control systems and apparatus
US2864943A (en) * 1954-02-24 1958-12-16 Motorola Inc Central station interrogation via relays of unattended data satellites which answer back
US3655915A (en) * 1970-05-07 1972-04-11 Gen Datacomm Ind Inc Closed loop test method and apparatus for duplex data transmission modem

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840797A (en) * 1952-08-14 1958-06-24 Westinghouse Electric Corp Supervisory control systems and apparatus
US2864943A (en) * 1954-02-24 1958-12-16 Motorola Inc Central station interrogation via relays of unattended data satellites which answer back
US3655915A (en) * 1970-05-07 1972-04-11 Gen Datacomm Ind Inc Closed loop test method and apparatus for duplex data transmission modem

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3952163A (en) * 1972-04-24 1976-04-20 General Datacomm Industries, Inc. Method and apparatus for testing in FDM system
US4039751A (en) * 1972-04-24 1977-08-02 General Datacomm Industries, Inc. Method and apparatus for closed loop testing of first and second modulators and demodulators
US3892923A (en) * 1972-08-16 1975-07-01 Philips Corp Supervision arrangement for a pulse code-modulation system
US4013956A (en) * 1974-05-09 1977-03-22 U.S. Philips Corporation Telecommunication system with automatically switched modems
US4004097A (en) * 1975-01-03 1977-01-18 Badger Meter, Inc. Automatic meter reading device
US4064459A (en) * 1975-07-09 1977-12-20 Siemens Aktiengesellschaft Method of automatically testing the serviceability of a data transmission system
US4055808A (en) * 1976-05-20 1977-10-25 Intertel, Inc. Data communications network testing system
US4129756A (en) * 1976-09-24 1978-12-12 Le Material Telephonique Telephone exchange signalling unit
FR2423934A1 (fr) * 1978-04-17 1979-11-16 Cea Elektronik Automat Gmbh Dispositif a boucle pour installation de transmission de donnees
US4247934A (en) * 1978-07-01 1981-01-27 Te Ka De Felten & Guilleaume Fernmeldeanlagen Gmbh Testing system for data transmission paths
US4271514A (en) * 1978-09-06 1981-06-02 Te Ka De, Felten & Guilleaume, Fernmeldeanlagen Gmbh Loopback test for data transmission paths
US4498186A (en) * 1980-10-10 1985-02-05 At&T Bell Laboratories Data set diagnostic system
US4402082A (en) * 1980-10-31 1983-08-30 Foster Wheeler Energy Corporation Automatic line termination in distributed industrial process control system
US4529979A (en) * 1981-09-07 1985-07-16 Hitachi, Ltd. Remote return loop control in a data transmission system
US4530085A (en) * 1982-04-07 1985-07-16 Hitachi, Ltd. Reconfiguration control method for a loop-type data network
US4607139A (en) * 1983-06-30 1986-08-19 International Business Machines Corp. Interface module for telephone lines
US4977579A (en) * 1984-06-14 1990-12-11 The United States Of America As Represented By The Secretary Of The Navy Test set for a navigational satellite receiver
US4766594A (en) * 1985-05-20 1988-08-23 Fujitsu Limited Digital network system having arrangement for testing digital subscriber line
US5272705A (en) * 1991-04-15 1993-12-21 Mitsubishi Denki Kabushiki Kaisha Semiconductor integrated circuit device
US5463633A (en) * 1994-02-22 1995-10-31 Rockwell International Corporation Use of at commands to test modem with HP3065
US5881066A (en) * 1995-03-01 1999-03-09 Lepitre; Didier System for testing a transmission link
US20080089492A1 (en) * 2004-08-11 2008-04-17 BSH Bosch und Siemens Hausgeräte GmbH Circuit Arrangement for Suppressing Interference Signals in the Receive Branch of a Modem of a Household Appliance
US20080095220A1 (en) * 2004-08-13 2008-04-24 Bsh Bosch Und Simens Hausgerate Gmbh Circuit Arrangement for Suppressing Interfering Signals in the Receiving Branch of a Modem of a Household Appliance

Also Published As

Publication number Publication date
JPS4826406A (de) 1973-04-07
GB1399659A (en) 1975-07-02
DE2231869A1 (de) 1973-02-15
DE2231869B2 (de) 1980-08-28
BE787359A (fr) 1973-02-09
CA951381A (en) 1974-07-16
DE2231869C3 (de) 1981-06-19
IT959320B (it) 1973-11-10
JPS5528449B2 (de) 1980-07-28
FR2150020A5 (de) 1973-03-30

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Owner name: FIRST PENNSYLVANIA BANK N.A., PENNSYLVANIA

Free format text: SECURITY INTEREST;ASSIGNOR:GENERAL DATACOMM INDUSTRIES, INC.;REEL/FRAME:005258/0104

Effective date: 19900110

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